While, as will be understood from the following description, the present invention was developed for generating accurate and time-critical propulsion commands for a vehicle's propulsion system.
Propulsion systems in vehicles, such as vertical takeoff and landing aircraft, satellites and ejection seats, provide forces for controlling the operation of the vehicle. These propulsion systems are controlled by controllers that provide control distribution commands to the propulsion systems. The control distribution commands must provide timely and accurate commands in order for the propulsion system to keep the vehicle operating within predefined limits. For example, the controller in a vertical takeoff and landing aircraft must accurately supply control distribution commands to the propulsion system according to analysis of pilot entered commands, aircraft position and motion, and predetermined limits of the propulsion system, aircraft, and pilot. If the control distribution commands are untimely or inaccurate, jet engine response can lag or misinterpret pilot inputs to the point of causing dangerous pilot induced oscillations. If the control distribution commands are inaccurate, jet engine total flow requirements will not be satisfied leading to engine flameout, degraded performance, or catastrophic failure.
Currently, controllers provide control distribution commands using iterative or multiple step algorithms implemented on digital microprocessors. This approach includes linear optimization or pseudo-inverse procedures that are inherently iterative in nature and have varying times of convergence. Iterative algorithms, when used for complex vehicle control, require extensive calculations and thus, have difficulty performing the required computations in real-time. When the iterative and multiple step algorithms cannot be executed in real-time, non-optimal approximate solutions are generated, thereby reducing the accuracy of the control distribution commands.
Another method of generating control distribution commands is a non-iterative linear technique, which uses mode switching when control limits are reached. This results in complex mode switching logic that is impractical to implement and verify. Another method implements multi-dimensional linearly interpolated data tables. This method requires excessive memory to store the data and is unable to execute the linear interpolation algorithms in real-time.
In summary, the present methods for providing control distribution commands require excessive microprocessor memory and complex mode switching, and are generally insufficient for providing real-time implementation.
The present invention is directed to overcoming the foregoing and other disadvantages. More specifically, the present invention is directed to providing a method and system for generating accurate control distribution commands in real-time.